Traffic control system



Aug. 17, 1937. GREEN 2 ,090,292

' TRAFFIC CONTROL'SYSTEM 8 dllllllj INVENTQR.

PAUL GQEEN, C BY M, M 1 MW ATTORNEYS.

Patented Aug. 17, 1937 UNITED STATES PATENT OFFICE TRAFFIC CONTROL SYSTEM Application December 13, 1930, Serial No. 502,137

4 Claims.

This invention relates to a functionally and structurally improved traffic control system, capable of use in numerous different associations, but primarily intended to be employed at the point of intersection of two vehicle lanes such as roads used primarily by automotive trafiic.

In certain respects, the present invention is primarily intended for use at the point of intersection of a highway and cross street; or at the point of intersection of a vehicle lane which normally has a major traffic flow by a vehicle lane which has a minor or intermittent traffic flow. Under these circumstances, and by means of the present invention, right of way is accorded normally to the highway, but in the event that vehicles are awaiting the right of way in the cross street, such right of way is transferred to the cross street for a period of time adequate for the vehicles to cross or turn into the highway. Where so employed, it is an object of the present invention to accord right of way to the cross street only when necessary and also in a manner such that minimum interruption to normal traffic flow will occur.

A further object is that of furnishing a layout of apparatus functioning in an improved manner and so that right of way can not be maintained for an indefinite period in favor of the cross street even if a large number of vehicles are awaiting such right of way. However, by means of the present invention, right of way will be accorded the cross street to permit traffic in the latter to proceed at the earliest possible moment after the expiration of the cross. street right of way period consistent with the ordinary and minimum requirements of the highway traffic.

A further object of the invention is that of providing an apparatus which, if installed at intersections of certain types will at no time interrupt the right of way of vehicles moving along certain paths of travel where such paths do not intersect the path of travel of other vehicles. This. constant maintenance of right of Way may of course always be qualified by for example an independent interruption thereof for the purpose of permitting pedestrians to cross as well as in the case of emergency vehicles such as fire engines and ambulances passing along the vehicle lanes either over or in proximity to the point of intersection.

Another and in certain aspects quite independent object of the invention is that of funishing an apparatus by means of which right of way is controlled in either one or both of the vehicle lanes consistent with the necessity for interrupting and according right of way. In other words and for the sake of example, a vehicle travelling over one of the lanes and desiring to make a left turn into the other lane, may be free to do so without it being necessary to interrupt the right of way to approaching traffic. In this case by means of the present invention, no such interruption will occur. However, if interruption of right of way is necessary to permit the vehicle to move in the manner afore noted-and whether due to the fact that the driver is timorous or due to the actual traffic densitya layout of apparatus according to the present invention will operate in the manner required to render the movement of the vehicle possible.

Still another object is that of furnishing a traffic control system and a layout of apparatus embodying said system which apparatus will include relatively few parts each individually simple and rugged in construction these parts operating over long periods of time with freedom from mechanical and electrical difficulties.

With these and other objects in mind, referenceis had to the attached sheet of drawing illustrating one practical embodiment of the invention, and in which:

Fig. 1 represents diagrammatically an intersection of a highway by a cross street with apparatus installed at this point and by means of which the teachings of the present invention may,

be practiced; and

Fig. 2 is a similar view showing the control apparatus employed. I

As afore brought out, the present invention is in many respects of especial value when employed in connection with an intersection involving a highway and a cross street. It is also in many respects of great utility where this intersection is 2.1 intersection embracing for example a cross street which ends at a highway and does not continue beyond the same. Thus, in the annexed drawing and the following description, the invention will be described in this connection. However, it will be understood that the present invention might be advantageously employed in,

connection with the intersection of two vehicle lanes having substantially equal trafiic density or dignity, and/or that the lanes might each continue beyond the point of intersection and that the layout of apparatus might be modified according to the needs of the actual point of installation thereof. In other words, the drawing and specification are to be construed as illustrative of one and in certain respects preferred form designate a roadway having one or more trafiic lanes, and more particularly is employed herein to designate the main highway or roadway carrying the heavier traffic, as street A in Fig. 1, at an intersection.

The term cross street is used herein to designate a roadway of one or more trafiic lanes meeting or crossing a highway and more particularly a roadway having less trafiic than the highway, as for example the street B in Fig. l is considered a cross street intersecting the highway A.

The term approach is used herein to designate a portion of a roadway or street at an intersection in which trafiic may approach the intersection, and is convenient for separating the sides of a particular street, as for example if the highway A in Fig. 1 is assumed to run north and south the portion of the highway on the north side of the intersection would be the north approach of highway A and the portion on the south side would be the south approach of high- Way A.

Thus, referring to Fig. 1, A indicates a highway, B a cross street which ends at the highway, C and D vehicle actuated controls which are connected to a timer E, the latter in turn governing the operation of a signal F.

The apparatus may be arranged in any desired manner and the signal includes preferably a lamp or housing within which there are colored bulbs, reflectors or lenses, these being conveniently green and red for the purpose of indicating right of way and interruption of right of way respectively. The vehicle actuated controls in the present example of the invention are preferably in the nature of pressure operated switches embracing pavement units to be traversed by a vehicle approaching the intersection. Thus, the weight of the vehicles closes these switches, but if desired, any other form of vehicle actuated control might be employed.

In Fig. 2, the numerals 5 and 6 indicate power supply leads from any suitable source and to which for example the bulbs 8 to [2 inclusive are connected in 'a manner hereinafter brought out, these bulbs or other source of illumination being those contained within the signalling means F.

In the example'under consideration, the units I l and I2 indicate Go and Stop respectively for the cross street B; the units 9 and I0 indicate Go and Stop respectively for trafiic approaching the intersection along highway A and in one direction, and the unit 8 indicates Go for traflic moving over the highway in the opposite direction, it being understood that a single unit of the latter nature is employed usually only where an installation such as the present exists and that all of these units are visible to traffic approaching the intersections in the directions afore referred to.

13 indicates a motor which may be electrically driven and which preferably includes a reduction drive (not shown) so that the shaft l4 moves at relatively low speeds. This shaft is coupled to a driven shaft I5 by means of a clutch I6 of any suitable type which will properly permit a slippage when appreciable resistance to movement is encountered on the part of the shaft I5. The latter shaft mounts in the example given a control disk I! which has a conducting sector [8 and a non-conducting sector l9. An abutment or stop portion 20 forms a part of this disk and a latch element 2] cooperates with this part in order normally to maintain the disk against rotation despite'the continued movement of the drive shaft I4. The latch may be rendered inoperative by for example being connected to the armature of a solenoid 22 and there is provided adjacent the disk or in suitable electrical connection with the conducting sector l8 thereof a wiping ring 23 with which a brush 24 cooperates, this brush being connected to lead 5 through a lead 25.

Brushes 26 and 21 cooperate with the disk faces and in the example given are spaced Brush 26 through a lead 28 is disposed in series with the illuminating units II and I0, and is connected to lead 6, while brush 2! through lead 29 is connected also to lead 6, it being noted that units I2 and 9 are in series with this latter brush. A vehicle actuated control C is interposed between leads 5 and 6 and has solenoid 22 embraced within its circuit. Arranged in shunt with this circuit is a lead 36 interrupted by a circuit breaker 3| which forms a part of a relay 32, thelatter being arranged in series with the vehicle actuated control D and between the leads 5 and 6. The unit 8 is simply connected across the leads 5 and 6, and consequently is in the example given energized at all times.

The position of the parts illustrated in Fig. 2 is the normal condition thereof. Under these circumstances, unit 8 will be energized and current will also flow through lead 25, brush 24 to sector I8, thence through brush 21 and lead 29 to units l2 and 9. Consequently, no right of way will exist on street B and right of way will be indicated in both directions on highway A. If now a vehicle approaches over street B, it will operate the control C thereby causing a functioning of the solenoid and a release of the latch member 2|, thus permitting the disk under the impulse of the drive shaft M to make one complete revolution. Preferably the speed of rotation of this shaft will be such that this one revolution will require sixty seconds. However, any other suitable cycle of timing may be resorted to. Almost instantly upon the control C being actuated, the disk will travel to an extent such that the brush 26 is in contact with sector I8 and brush 2'! is in contact with sector l9. This will result in units [2 and 9 being deenergized and in units H and in being energized. Accordingly, right of way in favor of vehicles moving along the highway in one direction is interrupted and right of way is accorded the cross street. This condition of the parts will maintain until the brush 2'! again contacts with sector l8 and brush 26 with sector l9 whereupon the right of way will be retransferred. Thereupon, the parts will finally assume the position shown in Fig. 2. If, however, an actuation of the control C occurs just after the cross street loses its right of way, it will be understood primarily that the highway will have at least an approximate thirty second right of way for the reason that this period of time will be required for the sectors of the disk to move past the brushes with which they are cooperating. However, even although the vehicle has moved beyond the control and the latter is no longer actuated, the layout of apparatus will function to accord right of way to the vehicle in the cross street after a lapse of such period of time. This will occur for the reason that a functioning of control C will energize the solenoid 22 and cause the latch 2| to be brought into contact with the lead 33. Thus, current will flow through the latch and through lead 34 which is connected to lead 29. Consequently, the solenoid is locked in and the latch will accordingly clear the stop member 20 as the latter moves in proximity thereto. Consequently, the right of way is retransferred tothe cross street and with such retransfer, locking in of the latch ceases due to the fact that brush 2'! is no longer in contact with sector l8.

Control D is preferably in the center of the highway and in a path of travel which will be normally intersected by vehicles desiring to make left hand turns into the cross street. Relay 32 is of the type which provides a certain time delay before closing switch 3|. For the sake of example, one may say that the vehicle actuated control D must be energized by a vehicle moving at a speed of five miles an hour or less for the relay to function. Consequently, in the case of vehicles which are moving along the highway and accidently traverse the control D, it may ordinarily be presumed that their speed of movement will be well above five miles an hour so that 20 there will be no danger of operating the relay.

Likewise, vehicles which approach the intersection over the highway A and turn smartly into the cross street by means of a left hand turn, will cause no functioning of the relay. Such turning into the cross street may occur due to the fact that there is no traific approaching over the highway in the opposite direction or due to the fact that despite such approaching traffic, the operator of the vehicle is sufficiently skilled 30 to pass between vehicles in the opposed trafilc flow which are spaced from each other to only a minor extent. However, if, due to heavy opposed traflic or for the reason that the driver is somewhat timorous, it becomes necessary to slow down or to stop in advance of making a left hand turn, the speed over the vehicle actuated control D will be five miles per hour or less. In such case, the relay 32 will function, causing a closing of the circuit breaker 3| and a flow of current 40 through the solenoid 22 in all respects similar to the example heretofore given.

Thus, among others, the several objects of the invention as. specifically afore brought out are achieved. Obviously, numerous changes in the 5 construction and rearrangements of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

5 1. A traffic control system for a T intersection of a highway and a cross street terminating at said highway and comprising signalling means for said highway for according and interrupting right of way to one approach of said highway 55 adjacent said cross street, other signalling means for continuously according right of way to traffic on the other approach of said highway and proceeding along said highway, further signalling means for according and interrupting right 60 of way in said cross street, a trafiic actuated de vice located in said other approach of said highway and adapted to be actuated solely by vehicles travelling slowly in preparation for making a turn interfering with traffic proceeding 65 along said highway from said one approach and not to be actuated by traffic travelling rapidly in said other approach to proceed along said highway, and a timing mechanism connected to the signalling means for said one approach of 7 said highway and for said cross street and to said traffic actuated device and adapted to be operated by such trafiic actuation of said device to cause the first signalling means to interrupt right of way in said one approach of said highway and the cross street signalling means to accord right of way.

2. A trafiic control system for a T intersection of two substantially parallel and opposite trafiic lanes with an interfering third lane terminating at said intersection, comprising a stop signal for one of the parallel lanes adjacent said third lane, means so disposed as to be actuated only by a unit of trafiic in the other parallel lane taking a, position to make a turn across the first parallel lane and not by through traflic in said other parallel lane, means to be actuated by said trafiic actuatable means when the latter is actuated, to display said stop signal to the first parallel lane, and a go sign-a1 and means displaying said go signal continuously for through trafiic in said other parallel lane.

3. A traflic control system for a T intersection of two substantially parallel and opposite trafiic lanes with an interfering third lane terminating at said intersection, comprising go and stop signals for one of the parallel lanes adjacent said third lane and also for said third lane, a go signal only for through traffic in the other parallel lane, means so disposed as to be actuated only by a unit of traffic in the other parallel lane taking a position to make a turn across the first parallel laneand not by through traffic in said other parallel lane, means normally displaying only the go signal in said one parallel lane and the stop signal in said third lane and adapted to be actuated by said traffic actuatable means when the latter is actuated to extinguish display of said normal go and stop signals and to display the stop signal in said one parallel lane and the go signal in said third lane, and means displaying continuously said go signal for through traffic in said other parallel lane.

4. A trafi'ic control system for a T intersection of two substantially parallel and opposite trafiic lanes with an interfering third lane terminating at said intersection, a stop signal for one of the parallel lanes adjacent said third lane, means arranged to be actuated only by trafiic in the other parallel lane preparing to make a turn across the first parallel lane and not by through traffic in the latter lane, and a signal control mechanism for normally maintaining said stop signal extinguished and adapted to be operated by actuation of said tr-affic actuated means to display said stop signal for a time period and then extinguish said stop signal for a time period to first stop the trafiic in the first parallel lane so as to permit the turning trafiic to proceed and then to permit the tr'afiic in the first parallel lane to proceed before any further display of the signal can be so caused by further trafiic actuation, said traffic actuated means comprising a traffic actuatable device in said other parallel lane and a delayed action element connected to be operated by each actuation of said device to render actuation eifective to so operate said mechani sm only when such actuation is relatively prolonged as by a unit of traffic slowly traversing said traific actuatable device in preparing to make said turn, and a go signal and means displaying said go signal continuously for through traflic in said other parallel lane.

PAUL GREEN. 

